Screw-tap



(No Model.)

3., G. NUGENT.

SCREW TAP.

Patented Nov. 24, .1885.

UNITE STATES ATENT. tribe.

RICHARD G. NUGENT, OF PITTSBURG, PENNSYLVANIA.

SCREW-TAP.

SPECIFICATION forming part of Letters Patent No. 330,999, dated November24, 1885.

Application filed June 8, 1885. Serial No. 167,953. (No model.)

To all whom it may concern.-

Be it known that I, RICHARD O. N UGENT, a citizen of the United States,residing at Pittsburg, in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements inExpanding Taps, of which the following is a full, clear, and exactdescription.

The object of the invention is to expand without tilting thethread-cutting dies; to regulate the amount of expansion of said dies;to provide means whereby the expansion shall be uniform at all points ofthe cuttingedges of said dies, and to simplify and render less expensivethe construction of the tap.

The invention consists in the means hereinafter described for attainingsaid object.

In the drawings, Figure 1 represents a front elevation of the tap withthe annular faceplate removed; Fig. 2, a side elevation with partsbroken away; Fig. 3, a longitudinal median section of tap; Fig. 4, atransverse section of same, taken through the plunger pin.

Similar letters of reference indicate corresponding parts throughout thedifferent views.

A represents the body of the tap, provided with the ordinary spindle a,by which it is secured in the lathe or other suitableoperating-machine.Said main body surrounds a cylindrical chamber, a',within whichreciprocates the plunger B.

c are radial slots, in which the threaddies work; and d are longitudinalbeveled grooves, in which are secured the reamers D.

The plunger B .is provided with a transverse pin-hole, b, in its rearextremity .through which, and through longitudinal slots of in the bodyA, passes a pin, 12. The extremities of said pin extend outwardly beyondthe periphery of body A, and through oblique slots 6 formed in the ringE. Said ring rests against a shoulder, a, formed on the outside of bodyI A, and is held in place by a retainingcollanf, secured by screws tosaid body. A lever, e, is attached to or made integral with the ring. Bythis construction it will be seen that when the lever e is thrust fromside to side the plunger B will be reciprocated. The forward extremityof the plunger B is reduced to the form of a frustum of a cone, and hasa series of die-grooves, 12 which have beveled sides for the purpose ofholding the dies in place. The dies F have their inner extremitiesbeveled to correspond with the slope of the conoid extremity of theplunger, by which construction all parts of the outer extremities ofsaid dies are equally projected beyond the body A when the tap isexpanded. Said inner extremities of the dies are provided with grooves fto cause them to dovetail with the plunger. Upon the outer end of theplunger is a setscrew, G, whose head is of somewhat greater surface thanthe area of the orifice h of the annulus H. The latter is secured to thebody A by screws or other suitable means.

The pipe, valve, or other article to be operated upon is first reamedout while the thread-dies are in retracted position. The lever e is thenoperated, and the plunger 13, through the medium of theobliquely-slotted ring E and pin 1), is thrust forward. The conical endof said plunger, acting upon the internal extremities of the thread-diesforces the latter outward. The extent of the expansion of the dies isdependent upon the screw G, which is forced against the annulus Hwhenever the plunger is reciprocated, and thus limits the outwardmovement of the latter. The thread is then cut, the plunger retracted,and the tap removed.

It will be seen that by my construction the thread-dies have at alltimes a solid hearing, that there is no tilting of the dies, and thatall parts of the latter are expanded and retracted uniformly.

Having thus described my invention,what I claim is The combination, withthe body A, having inner chamber, or, dies F, and the reciprocatingplunger B, of the headed end screw, G, and annulus H, the latter havingan orifice,

it, smaller than the head of said screw, whereby the screw may beadjusted to regulate the throw of plunger from the outside of body.

RICHARD C. NUGENT.

Witnesses:

HENRY O. LYON, LENox SIMPSON.

